History
While the theory of vacuums dates back to ancient times, Robert Boyle invented the first vacuum pump in the 1700's. This device allowed experimental confirmation of the concept that pressure times volume is proportional to temperature, a relation known either as Boyle's law or Mariotte's law. These fundamental laws of nature are invaluable to our ability to engineer devices ranging from plumbing to engines. In the twentieth century, methods have been developed that allow precise coating of materials throuch evaporation and condensation (PVD) or even chemical reactions (CVD) on a surface in a vacuum. Furthermore, the development of sputtering techniques (bombardment with particles) allows further functionalization of surfaces in a clean, controlled and reproducable environment.
Principles of Operation
Many approaches to nanotechnology require a vacuum. For instance, Lowering the pressure to evaporate solvents is a crucial component of synthetic chemistry (the source of molecules for nanotechnology), enabling the chemist to dissolve molecules in a variety of solutions, carry out reactions and remove the solution leaving behind the molecules of interest. Low to medium vacuum will typically suffice these applications, ranging in pressure from 1 - 10-5 Torr. Particle beams (whether for lithography, diffraction or microscopy), epitaxial growth or atomic positioning via STM require an extremely clean environment in order to create and observe atomic precision. For such applications, High Vacuum (HV ) or even UltraHigh Vacuum (UHV) are preferred, ranging in pressure from 10-6 to 10-9 Torr or lower.
Advantages
- Provides an extremely clean environment
- Allows particle beams to propogate unimpeded by gasses
- Low pressure allows evaporation and epitaxy of relatively large molecules
Disadvantages- Difficult to access & interact with the sample in a vacuum without disrupting or contaminating the vacuum.
- Many substances of interestest (especially biological) are not stable at low pressures
Vacuum Product Companies
